Gossypol isatin schiff base compounds with antitumor activities and a method of preparing the same

A gossypol isatin Schiff base compound with antitumor activities represented by formula I: R1 and R2 are independently hydrogen, alkyl, cycloalkyl, alkoxy, nitro, halogen, unsubstituted or substituted phenyl, or unsubstituted or substituted benzyl. A method of preparing the compound of formula I is also disclosed.